Inertia vs. Gravity

If inertia is different than gravity than wouldn't there possibly be more energy in a falling body of water than in water drawn from a given depth of water? Isn't there some aspect of thermodynamics that favors the body in motion?

Velocity gained from water pressure (created by water depth) seems like it would be less than velocity gained from water falling from the same height.

Take a twenty foot tall tank of water. To draw 720 gpm from the bottom of the tank (assuming .42 psi per foot) would produce x amount of energy.

If the same volume of water (720 gpm ) were to fall from the top of the twenty foot tower, wouldn't the final velocity (upon reaching the level of the bottom of the tank) be aided by the fact that it is already a body in motion?Whereas the water at the bottom of the tank, although it is under pressure, it must start out as still.

Isn't there some aspect of thermodynamics that favors the body in motion? Also, isn't the fact that 100 lbs. per second (720 gpm)is hitting the ground level at 30 mph (44 fps) with an impact of 2000-3000 lbs. causing any higher level of total energy output than what could be obtained from drawing the same volume from the bottom of the tank? Isn't inertia different than gravity?